SENTRON 3VA1120-6EF36-0BC0 — Line Protection MCCB with High Interrupting Capacity
The Siemens 3VA1120-6EF36-0BC0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection, with a rated continuous current Iu of 20 A across the 40 °C to 50 °C ambient range. At 240 V it interrupts 220 kA, at 415 V it handles 154 kA, and at 440 V it clears 121 kA — figures that place it in the high-breaking-capacity tier for industrial distribution panels where fault current levels are severe. The TM240 thermal-magnetic overcurrent release provides fixed thermal and magnetic trip settings, so the coordination study determines the selectivity, not field-adjustable dials. The 3-pole design with 800 V rated insulation voltage (Ui) suits it for 400 V three-phase systems with headroom. An undervoltage release (UVR) is integrated as standard — the auxiliary release design is the UVR type, meaning the breaker trips on loss of control voltage, which is typical for emergency-stop or safety-shutdown circuits where a drop-out on undervoltage is required. Two HQ auxiliary switches (3VA9608-0BB11) are built in for status feedback to a PLC or annunciator panel.
Thermal Derating and Ambient Constraints
The breaker holds its full 20 A rating from 40 °C through 50 °C. At 55 °C it derates to 19.2 A, at 60 °C to 18.8 A, at 65 °C to 18.4 A, and at 70 °C to 18 A. The operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. For a panel that runs hot — say a non-ventilated enclosure near a furnace line — the 55 °C derating to 19.2 A is the figure to use in the load calculation, not the 20 A nameplate.
Panel Integration and Physical Fit
The breaker measures 70 mm deep, 76.2 mm wide, and 130 mm high. The 76.2 mm width is a standard 3-pole MCCB footprint for DIN-rail or screw-mount panel assembly. Front-face protection is IP40, so the breaker is suitable for enclosed distribution boards where tools or fingers are the primary concern, not washdown. No communication function, no phase failure detection, no ground fault monitoring — this is a straightforward line-protection device without embedded metering or remote-trip capability.